Various seismic phenomena, such as tremors and catastrophic earthquakes, are known to cause devastating loss of life, injury, property damage directly associated with the moving of the earth's surface, as well as collateral damage, both in terms of human life and property, resulting from fires that start as a result of damaged electrical power lines and ruptured gas mains. While much has been learned about the mechanisms that cause various seismic phenomena, such as tremors and catastrophic earthquakes, there is presently no means for predicting when or where seismic activity will occur and thus there has been no means of providing an early warning that would reduce the number of casualties, and perhaps prevent much of the collateral property damage associated with seismic activity. What is needed is an early warning system that could provide enough notice to, at the least, facilitate evacuations and allow electrical and gas systems to be shut-off.
It will be recognized by those skilled in the art that earthquakes, and other seismic phenomenon, arise from stresses introduced by various subsurface mechanisms. It is believed that these stresses introduce micro-fractures in the subterranean strata that grow or continue to accumulate until catastrophic macro-fracture suddenly occurs.
Subsurface strata store gases and fault zones are well known storage sites for hydrocarbon gases. When micro-fractures develop within buried strata, the trapped gases are more free to migrate in a buoyant or vertical sense. Even in stable and rather dense formations, geologists have been able to verify measurable and often significant migrations of hydrocarbon gases.
In this regard, it has been known in the field of geophysical prospecting that gaseous substances associated with subterranean deposits of minerals, hydrocarbons, such as coal, oil and gas, and other materials migrate towards the earth's surface. In this regard, U.S. Pat. No. 4,065,972 issued on Jan. 3, 1978, to Holub et al. discloses a method and apparatus for detection of subterranean deposits based on this phenomenon. It has also been learned that these methods of geophysical prospecting are often inaccurate as the vertical migration of gaseous substances tends to follow fault lines and other lines of demarcation in the substrata of the earth's surface.
U.S. Pat. No. 4,297,574 issued on Oct. 27, 1981, to Card et al. discloses a method for detecting radon gas decay products and U.S. Pat. No. 4,786,804 issued on Nov. 22, 1988, to Ilmasti discloses a device for measuring radon gas in the soil.
However, what is needed is an earthquake early warning system that provides notice of an imminent seismic activity such as tremors and/or earthquakes so as to allow time to facilitate evacuation of threatened structures and further facilitate shutting-off threatened electrical systems and gas mains.
Accordingly, it is an object of this invention to provide a system for providing an early warning that seismic activity such as earthquakes and/or tremors is imminent.
It is a further object of the present invention to provide such an earthquake early warning system by detecting sudden or sustained increases in the migration of subterranean gases towards the surface of the earth.
Other objects and advantages over the prior art will become apparent to those skilled in the art upon reading the detailed description together with the drawings as described as follows.